(My first job after leaving school, was in the coal mines of South Wales. Hose pipes of various types were used; sometimes for water; sometimes for compressed air. They were not known as hosepipes, but as 'bags'. DH.) There is nothing better than a hosepipe (!) for shaping curved borders and beds in the garden. The better quality ones - that don't kink - are best, but a 'cheapy' filled with water will also do the trick. Simply lay the hose along the outline that you envisage, and move it about until you get the shape required. Fewer, sweeping curves, are always better than lots of squiggles. But, if you like squiggles, then go for them.  
A typical small garden with the regulation 45cm (18in border) It is uninteresting in the first place, so the motivation for looking after it soon wanes.
The difference a few curves can make. 
background planting of assorted shrubs, which will be followed by a mixture of bedding plants to fill up the gaps.........and a 'cosmetic' finish of ornamental bark chippings, to give us this 
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